A smart card contains an integrated-circuit chip (IC chip) having one or more components, such as a microprocessor, a card operating system, a security module, and/or a memory, so as to allow the holder to perform certain operations. A smart card may provide calculation, encryption, bidirectional communication, and/or security functions, and may be convenient to carry. For these and other reasons, various smart cards are used in a diverse range of applications such as traffic, medical and heath, identification, distribution, and/or civil applications.
Smart cards are classified into contact type cards, non-contact type cards, and combinations thereof (i.e., combination or hybrid type cards) based on the interface method of the card. A contact type smart card should be inserted into a reader to use it. That is, the contact type card can receives electricity and a clock signal for its operation via physical contact. Some card readers for a contact type smart card hold an inserted card so as to prevent the card from being removed before the end of communication between the reader and the card. A large amount of data can be transmitted to or from a contact type smart card as compared with the case of a non-contact type smart card. The ISO/IEC 7816 protocol is provided for contact type smart cards. In contrast, a non-contact type smart card can communicate with a reader at a distance from the reader. Thus, it may not be necessary to insert a non-contact type smart card into a reader to use the card. Protocols such as ISO/IEC 10536 and ISO/IEC 14443 are provided for non-contact type cards.
One example of a contact type smart card is a subscriber identification module (SIM) card used in a cellular phone, such as a cellular phone configured for use with a GSM (Global System for Mobile communications) communication system. A SIM card is a module that provides information about a particular user based on the name and password of the user. Since a SIM card contains information about its user, the user can, for example, use another person's cellular phone as the user's own by inserting the SIM card into the other person's cellular phone (in which case, the bill would be issued to the user associated with the SIM card).
According to the interface regulations specified in the ISO 7816 protocol for contact type smart cards, eight contact pads C1 to C8 are provided for a SIM card. The functions of the contact pads C1 to C8 are shown in Table 1 below.
TABLE 1PIN #ASSIGNMENT (ISO 7816)C1VDD (SUPPLY VOLTAGE)C2RST (RESET SIGNAL)C3CLK (CLOCK SIGNAL)C4RESERVEC5VSS (GROUND)C6VPP (PROGRAMMING VOLTAGE)C7I/O (DATA INPUT/OUTPUT)C8RESERVE
Referring to Table 1, the contact pad C1 is used to receive power through an outside interface for the SIM card. The contact pad C2 is used to receive a reset signal for resetting an internal circuit of the SIM card. The contact pad C3 is used to receive a clock signal from an outside interface. The clock signal may be used for operating a microprocessor embedded in the SIM card. The contact pad C5 is used as an electrical ground between the SIM card and an outer interface. The contact pad C6 is used as a power supply pin for supplying a programming voltage (VPP) to an electrically erasable programmable read only memory (EEPROM) embedded in the SIM card. The contact pad C7 is used for data communication between the SIM card and an outside interface by a half-duplex communication scheme. Meanwhile, the contact pads C4 and C8 are reserved pads that are not yet specified in the ISO 7816 protocol.
According to the ISO 7816 protocol, 9600-bps, 19200-bps, and 38400-bps transmission rates are allowed. Therefore, the ISO 7816 protocol is usually used for applications requiring a low communication bandwidth, such as automated teller machines (ATMs) and visitor identification certificating devices. However, as electronic commerce technologies using the Internet and cellular phones are developed, and transmission of large data such as audio and video files are increasingly demanded.
Therefore, to provide an increased variety of services using a smart card, more contact pads may be added to the smart card, and/or an additional chip may be embedded in the smart card. However, as described above, the number and functions of the contact pads C1 to C8 are already defined for SIM cards.